I love
Casimir. Not enough to use it, but I do think it's very cool and has a lot of character. One of my very close friends has the middle name
Casimir, and it just
works. It's one of those names that goes great in the middle name spot, I think because of how it sounds. Some possible combos (from my list) would be
Adrian Casimir,
Evren Casimir,
Matthias Casimir, and, if you wanted to do something completely over-the-top and ridiculous,
Servatius Casimir.